Effect of interface on mid-infrared photothermal response of MoS2 thin film grown by pulsed laser deposition

Abstract

Here we report mid infrared (mid-IR) photothermal response of multi layer MoS2 thin film grown on crystalline (p-type silicon and c-axis oriented single crystal sapphire) and amorphous substrates (Si/SiO2 and Si/SiN) by pulsed laser deposition (PLD) technique. The photothermal response of the MoS2 films was measured as changes in the resistance of MoS2 films when irradiated with mid IR (7 to 8.2 μm) source. We show that it is possible to enhance the temperature coefficient of resistance (TCR) of the MoS2 thin film by controlling the interface through proper choice of substrate and growth conditions. The thin films grown by PLD were characterized using XRD, Raman, AFM, XPS and TEM. High-resolution transmission electron microscopy (HRTEM) images show that the MoS2 films grow on sapphire substrate in a layerby-layer manner with misfit dislocations. Layer growth morphology is disrupted when grown on substrates with diamond cubic structure such as silicon due to growth twin formation. The growth morphology is very different on amorphous substrates such as Si/SiO2 or Si/SiN. TheMoS2 film grown on silicon shows a very high TCR (-2.9% K -1 ), mid IR sensitivity (∆R/R=5.2 %) and responsivity (8.7 V/W) as compared to films on other substrates.

MoS2 Thin Films Grown by Sulfurization of DC Sputtered Mo Thin Films on Si/SiO2 and C-Plane Sapphire Substrates

“…Similar broadband absorption in the NIR and MIR regions was obtained by Goswami and et al for the bulk MoS 2 films. 24 As expected, the absorption of the films increased with the film thickness. Owing to this strong absorption of the films in these regions, it is considered that they can be used for IR detection applications.…”

“…15 These properties make MoS 2 a promising material in future nanoscale electronic and optoelectronic device applications such as photocatalysis, 16 photodetectors, 17 biosensors, 18 gas sensors, 19 phototransistors, 20 field-effect transistors (FETs), 21 solar cells 22 and light-emitting diodes (LEDs). 23 There have been many various attempts including top-down and bottom-up methods such as mechanical exfoliation, 24 chemical exfoliation, 25 hydrothermal synthesis, 26 physical vapor deposition (PVD), 27 and chemical vapor deposition (CVD) 28 to produce MoS 2 thin films. Initially, researchers have intensely focused on the exfoliation method for obtaining monolayers of MoS 2 films and it is still the most commonly used method for the growth of MoS 2 films.…”

Recent Progress on Irradiation-Induced Defect Engineering of Two-Dimensional 2H-MoS2 Few Layers

“…2H MoS 2 multi-layers were grown through pulsed mid-infrared laser deposition [147] (wavelength of 7.0-8.2 µm). No any IR damage was reported.…”

Recent Progress and Future Prospects of 2D‐Based Photodetectors

“…Goswami et al demonstrated a TCR up to −2.9% K −1 at room temperature in pulsed laser deposition (PLD)–grown MoS 2 film on silicon substrate. Their reported MoS 2 bolometers were sensitive to mid‐IR irradiation (7–8.2 µm) with a responsivity of 8.7 V W −1 and response time on the order of 10 s . Superconductors are also known to show a very strong resistance dependence on temperature near the critical temperature T c , and have been proposed as sensitive superconducting bolometers .…”